The "New Way . . .

 I just love my Newway Seat Cutter.  The carbide cutters are adjustable, they give you the 46 and the 30 (just flip it over) and you can get a 60 degree too - and then you can achieve the seat width you want, and with some practice, you get a nice smooth seat finish by gradually decreasing the pressure on the spring-loaded handle.  It makes cutting seats fun, and it's not so messy.  I lap the valves in carefully with a low-speed drill (forward & reverse) and then hand-lap the final finish.  This is my KHK racer cylinders with big, honkin' valves.  They almost touch each other.  She's factory-ported and I just dig these K Models !